1. Field of the Invention
This invention relates broadly to endoscopic surgical instruments. More particularly, this invention relates to jaw assemblies for endoscopic biopsy forceps instruments.
2. State of the Art
Endoscopic biopsy procedures are typically performed with an endoscope and an endoscopic biopsy forceps device (bioptome). The endoscope is a long flexible tube carrying fiber optics and having a narrow lumen through which the bioptome is inserted. The bioptome typically includes a long flexible coil having a pair of opposed jaws at the distal end and manual actuation means at the proximal end. Manipulation of the actuation means opens and closes the jaws. During a biopsy tissue sampling operation, the surgeon guides the endoscope to the biopsy site while viewing the biopsy site through the fiber optics of the endoscope. The bioptome is inserted through the narrow lumen of the endoscope until the opposed jaws arrive at the biopsy site, which is typically a relatively large body cavity, e.g., the stomach or large intestine. While viewing the biopsy site through the fiber optics of the endoscope, the surgeon directs endoscope toward the sample tissue site, moves the jaws head on to the tissue site, and positions the jaws around the sample tissue. The surgeon manipulates the actuation means so that the jaws close around the tissue and a sample of the tissue is then cut and/or torn away from the biopsy site while it is trapped between the jaws of the bioptome. Keeping the jaws closed, the surgeon withdraws the bioptome from the endoscope and then opens the jaws to collect the biopsy tissue sample.
Not all biopsy sites are large enough to enable the surgeon to adequately direct the endoscope and the jaws in a desired manner to a sample site. For example, the esophagus is relatively narrow, and it is difficult to turn and orient the endoscope within the esophagus to thereby aim a jaw assembly exiting a lumen of the endoscope toward the desired sample site; the sample site being typically located lateral of the distal end of the endoscope. Thus, in esophageal applications, it is common for the jaws to exit the endoscope and continue through the esophagus and fail to properly engage the wall of the esophagus for biopsy sampling.
In addition, an esophageal biopsy tissue sampling procedure often requires the taking of several tissue samples either from the same or from different biopsy sites. Unfortunately, most bioptomes are limited to taking a single tissue sample, after which the device must be withdrawn from the endoscope and the tissue collected before the device can be used again to take a second tissue sample. The single-sample limitation of most bioptomes is due to the limited space between the biopsy forceps jaws.
Several attempts have been made to provide an instrument which will allow the taking of several tissue samples before the instrument must be withdrawn and the samples collected. Problems in providing such an instrument include the extremely small size required by the narrow lumen of the endoscope and the fact that the instrument must be flexible in order to be inserted through the lumen of the endoscope. Thus, several known multiple sample biopsy instruments are precluded from use with an endoscope because of their size and rigidity. These include the "punch and suction type" instruments disclosed in U.S. Pat. No. 3,989,033 to Halpern et al. and No. 4,522,206 to Whipple et al.
Related efforts have been made to provide a multiple sampling ability to an instrument which must traverse the narrow lumen of an endoscope. These efforts have concentrated on providing a cylindrical storage space at the distal end of the instrument wherein several tissue samples can be accumulated before the instrument is withdrawn from the endoscope. U.S. Pat. No. 4,651,753 to Lifton, for example, discloses a rigid cylindrical member attached to the distal end of a first flexible tube and having a lateral opening. A second flexible tube is coupled to a knife blade for moving the knife blade relative to the lateral opening in the cylindrical member. A tissue sample is taken by bringing the lateral opening of the cylindrical member upon the biopsy site, applying vacuum with the syringe to draw tissue into the lateral opening, and pushing the second flexible tube forward to move the knife blade across the lateral opening. A tissue sample is thereby cut and trapped inside the cylindrical knife within the cylindrical member. However, the device of the Lifton patent suffers from several serious drawbacks. First, the Lifton device is designed to sample laterally of the device by using a syringe to help draw the tissue into the lateral opening, yet the nature of esophageal tissue does not lend itself to being drawn by suction, as the tissue is fairly tough. Second, the Lifton patent requires substantial effort on the part of the surgeon and an assistant and much of this effort is involved in pushing tubes, an action which is counter-intuitive to classical biopsy sampling. The preferred mode of operation of virtually all endoscopic tools is that a gripping action at the distal end of the instrument is effected by a similar action at the proximal end of the instrument. Classical biopsy forceps jaws are closed by squeezing a manual actuation member in a syringe-like manner.
A more convenient endoscopic multiple sample biopsy device is disclosed in U.S. Pat. No. 5,171,255 to Rydell. Rydell provides a flexible endoscopic instrument with a knife-sharp cutting cylindrical sleeve at its distal end. A coaxial anvil is coupled to a pull wire and is actuated in the same manner as conventional biopsy forceps. Ostensibly, when the anvil is drawn into the cylinder, tissue located between the anvil and the cylinder is cut and pushed into a storage space within the cylinder. Several samples may be taken and held in the storage space before the device is withdrawn from the endoscope. While the device of Rydell is purportedly effective in providing a multiple sample tool, it is limited to the lateral cutting of relatively loose tissue, unlike the tough tissue found in the esophagus.
Generally, tough tissue like that found in the esophagus is more effectively sampled with a forceps having jaws, as disclosed in co-owned U.S. Pat. No. 5,542,432 to Slater et al. Slater et al. discloses an endoscopic multiple sample biopsy forceps having a jaw assembly which includes a pair of opposed toothed jaw cups each of which is coupled by a resilient arm to a threaded base member. The threaded base member of the jaw assembly is mounted inside a cylindrical sleeve and axial movement of one of the jaw assembly and cylindrical sleeve relative to the other draws the arms of the jaws into the cylindrical sleeve or moves the cylindrical sleeve over the arms of the jaws to bring the jaw cups together in a biting action. The arms of the jaws effectively form a storage chamber which extends proximally from the lower jaw cup and prevents accumulated biopsy samples from being squeezed laterally out from between the jaws during repeated opening and closing of the jaws and the lower jaw cup enhances movement of the biopsy samples into the storage chamber.
Co-owned U.S. Ser. No. 08/440,327 to Palmer et al. improves on this concept by providing super-elastic jaw arms and jaw cups to the jaws assembly. Super-elastic jaw arms are extremely flexible and repeatedly return to desired positions without fracturing or deforming. In addition, super-elastic jaw arms do not significantly plastically deform, even after repeatedly being opened and forced closed. This instrument excels at taking samples of tissue located in front of the jaw assembly.
However, as discussed above, the narrow space of the esophagus hinders the distal portion of the endoscope from adequately aligning the biopsy instrument in a head-on direction.